Substituted fluorobenzenes are known in the art and have found utility as intermediates, particularly for making insecticides, fungicides and herbicides. They are also useful for drugs or intermediates for drugs.
U.S. Pat. No. 2,861,095 relates to certain fluorocyclohexenes and to methods for their preparation. The patent describes a method for pyrolyzing vinylfluorocyclobutanes to fluorocyclohexenes at temperatures of 450.degree.-800.degree. C. The patent discloses at column 1, line 67 that temperatures above 800.degree. C. are undesirable because of the tendency of the vinylfluorocyclobutanes to be converted to difluorobenzenes rather than to the desired cyclohexenes.
U.S. Pat. No. 3,499,942discloses a process for making carbocyclic mono- and difluoroaromatic compounds by pyrolysis of an aliphatic fluorine containing compound with a conjugated compounds, e.g., a cyclic diene, at temperatures at 300.degree.-800.degree. C. Example 25 of the patent describes the pyrolysis of a mixture of butadiene and tetrafluoroethylene in the absence of an additional reagent at 600.degree. C. to produce a mixture of isomeric difluorobenzenes.